Optical Backplane Using Substrate-holograms for High-speed Data Communications

The limited bus bandwidth is a major bottleneck for efficient communication among processing components, memory modules, and other I/O interface units. In the conventional electrical backplane, the bandwidth of communication path is limited by signal-propagation delay, skew, power consumption, and capacitive effects. To solve these problems, Radiant Research, Inc., proposes a substrate mode holograms-based guided-wave optical backplane scheme that is capable of providing the equivalent interconnectivity and the architecture flexibility promised by three-dimensional optical interconnects while maintaining packaging reliability, low system insertion loss and cost-effectiveness. The total aggregate bandwidth is expected to be three orders of magnitude higher than that of electrical interconnection. The guided wave optical backplane employed is a waveguiding plate in conjunction with photo-polymeric multiplexed volume holograms. In the proposed scheme, the electrical connectors are positioned as usual, and the active optoelectronic modules including transmitters and receivers are placed on the bottom of the electrical backplane board, and a new broadcasting scheme is proposed to provide n.(n-1) even fanout for a backplane containing n boards. Thus the insertion or removal of circuit boards during normal operation does not affect their alignment. This approach also provides bi-directional signal broadcast capability, making the system compatible with existing electrical boards.